The present invention relates to an integrated circuit (IC) card, and more particularly to an IC card which can be used as an identification medium for personal identification and for preventing unauthorized use thereof.
In the past, a magnetic card has been used for a bank card or credit card. In a magnetic card system, a personal identification data for identifying an owner of the magnetic card, which is called a password is stored in the magnetic card, and an equality between the password electromagnetically read from the magnetic card loaded to a card reader and a password manually entered by the card owner is checked to determine whether the user of the card is a valid card owner. However, the following problems reside in the magnetic card.
(i) The password recorded on the magnetic card can be read by simple hardware and hence the use by an unauthorized person can be easily accomplished.
(ii) The password should be known only to the owner; however, hardware for writing the password is necessary and a person who prepares the card writes the password based on an application of the owner. As a result, a critical problem remains that there is a person other than the owner who can be aware of the password.
(iii) A security protection of an automatic machine such as a cash dispenser or vending machine is not perfect and the prevention of leakage of the password is not perfect. Nevertheless, the password cannot be changed by the owner and the card is used even after another person has become acquainted with the password.
For the problem (i) above, an improvement was proposed in Japanese Examined Patent Publication No. 53-6491 but it does not recognize and solve the problems (ii) and (iii) above, although Japanese Unexamined Patent Application (Kokai) No. 53-86144 discloses a dedicated password change device for cash card available for change at specified locations. Accordingly, the security against the forgery of the card and the unauthorized readout is not assured.
In recent years, an IC card which contains a microprocessor IC or memory IC has been developed. It is superior to the magnetic card in performance and memory capacity. A basic construction of the IC card is disclosed in Japanese Examined Patent Publication No. 53-6491 to Arimura, issued on Mar. 8, 1978 and Roland Moreno U.S. Pat. Nos. 4,007,355; 4,102,493; 4,092,524 and 3,971,916, but considerations on problems of the security have not sufficiently been taken. Technical trend of the IC card is described in NIKKEI ELECTRONICS Dec. 2, 1985, pages 275-292 and Dec. 16, 1985, pages 249-262. (This does not mean that those are prior art to the present invention.) Japanese Unexamined Patent Publication (Kokai) No. 59-123070 discloses a temporal transaction method using a temporally available password (not prior art).